Hollow metal propeller



F. H. LUENSE.

HOLLOW METAL PROPELLER.

APPLICATION FILED SEPT. 15. I916.

Patented Mar. 22, 1921.

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FREDERICK H. LUENSE, OF STAPLETON, NEVI YORK, AS$IGNOR lO AIRCRAFT PRO- PELLER CORPORATION, OF NEW YORK,

N. Y., A CORPORATION 01? NEW YORK.

HOLLOW METAL PROPELLER.

T 0 all whom it may concern Be it known that I, FREDERICK H. LUENsn, a subject of the Emperor of Germany, residing at Stapleton, county of Richmond, city and State of New York, have invented certain new and useful Improvements in Hollow Metal Propellers, of which the following is a specification.

' My invention relates to propellers and has special reference to such as are adapted for aviation service.

One object of my invention is to provide a propeller that shall. be sufficiently light and strong for aviation purposes, formed of stamped or die-formed sheet metal sections which can be produced in large quantities at small expense, and that shall not be subject to warping or coming apart under adverse service or climatic conditions. I prefer to use drawn sheet metal such as steel, hosphor bronze, and the like, but any suitable material may be employed, the sections being brazed or welded together at their meeting edges by any of the approved methods in use.

To attain the aforesaid objective results 1 divide the propeller into such sections as permit the use of dies for forming them and do not impair the strength of the resultant propeller at any vital point. The sections are joined in such manner that the operating characteristics of the propeller are not disturbed or altered by protruding seams and the structure is not distorted by the forces obtaining in flight.

Preferably, the sections are arranged to form a hollow propeller construction and a block of wood is inserted to fill the central portion or hub of the propeller and extends partially within the hollow interior of the blades, thereby relieving the hollow propeller hub of the crushing strains due to the shaft fastening bolts, and counteracting the gyroscopic and other strains induced in i ht.

Other objects and'advantages of my invention will be set forth hereinafter, and in order that my invention may be thoroughly understood 1 will now proceed to describe the same in the following specification, and will then point out the novel features thereof in appended claims.

' Referring to the drawings:

Figure 1 is a face elevation of a propeller constructed in accordance with my inven- Specification of Letters Patent.

Application filed September 15, 1916. Serial No. 120,214.

Patented Mar. 22, 1921.

tion, and constituting one embodiment thereof.

Fig. 2 is a side elevation of the same structure.

Fig. 3 is a perspective view of one section of the propellerblade.

Fig. 4 is a perspective view of the other section of the propeller blade.

Figs. 5, 6, 7 and 8 are sections respectively on the lines 55, 6+6, 77 and 8-8 of Fig. 1; and

Fig. 9 is a detail hub view of a propeller having three blades and constituting another embodiment of my invention.

Referring to Figs. 1 to 8 inclusive, the two-blade propeller here shown is formed of four sections, each of which extends from the central hub portion of the propeller to the tip of one blade. As shown in Figs. 3 and 1, each blade is comprised of two sections 1, 2, of which the edge 3 on one side of section 1 abuts the edge 1 on the opposing edge of section 2, whereas the edge 5 of the other side of section 1 abuts the opposing edge 6 of section 2. The sections comprising the other blade are duplicates respectively of said sections 1, 2, and the blades are alike for either the two blade type of propeller as shown in Figs. 1 and 2,01 the three blade type of Fig. 9.

Preferably, the abutting edges between sections and between blades are welded together either electrically or by means of the oXy-hydrogen or oXy-acetylene blowpipe, or the like but they may be brazed or joined in some other suitable manner. In the two blade type as indicated in Fig. 1, the central parts of the portions 11, 12 of sections 1', 2 are semicircular in contour and the central portions 13, 14c, 15 of the three blade type, as indicated in Fig. 9, are equal sectors corresponding to the number of blades. This will be true if more than three blades are employed.

A set of holes 17 in section 1 and a set of holes 18 in section 2 of the respective blades, are provided for bolts 22 which secure the propeller to the flanges 19 of the sleeve or hub which receives the driving shaft. The central portions of the respective propeller blades are provided with an equal number of bolt holes which are preferably distributed uniformly.

The several sections may be made of steel,

ably formed to the desired shape, under the oppositely placed circular steel reinforcing plates 21, are positioned within the central or hub interior of the propeller, and suitable holes are provided therein for the fastening bolts 24. The block of wood 20 and the plates 21 enable the fastening bolts to be firmly tightened without crushing the structure or distorting the blades, the latter being materially reinforced by the wood block extensions 22 and mutually strengthened against the stresses caused by the gyroscopic forces induced while in flight. Furthermore, it will be noted that each section on each face of the propeller is connected by the bolts 22 and the plates 21 to a section. on the same face so that the several blades are also mutually reinforced for this reason and the shape of the propeller is maintained.

Preferably the extensions 22 of the wood block 20 project for a considerable distance into the hollow interiors of the respective blades, the central opening 23 in the block 20 being in alinement with the shaft opening of the propeller and arranged-to receive the propeller hub. My invention is not restricted to the use of wood as a reinforcing body at the center, and other suitable materials may be substituted if desired.

As will be observed from the drawings, the propeller is divided into such sections as may be easily formed into the requisite shape, by dies or tools, to wit, each single blade is divided into two sections, one section comprising the front face of the blade and the other section the rear face of the blade,

the dividing line running along the-leading and trailing edges from the center to the top.

The structure also results in the formation of a hub portion for each blade of suitable construction for fastening to the flanged propeller hub. The sheet steel construction enables me to reduce to a minimum the harmful head resistance of the leading edges of the blades as well as providing the most' Fureflicient form for the trailingedges. thermore, the propeller of my invention lends itself readily to grinding, polishing,

plating or galvanizing, and will maintain,

its shape under all conditions of active service.

As will be understood, the invention may be embodied in propellers having twoor more blades, and various modifications may be effected within the spirit and scope of my invention.

I claim.

1. A propeller composed of die-formed sheet steel sections joined to form a unitary propeller structure and'having their joining edges extending along the leading and trailing edges of the propeller blade and a sheet metal'reinforcing plate secured to the pro-- peller structure at the hub.

2. A propeller composed of die-formed sheet metal sections joined to form a unitary propeller structure and having their joining edges extending along theleading and trailing edges of. the propeller blade said meeting edges being brazed or welded together and a solid reinforcing member at the hub extend.

portions of each blade section and bolts passing through corresponding holes connecting the respective plates with like faces of the blades.

5. A propeller composed of blades brazed or welded together at thecenter and reinforced by two oppositely disposed central steel plates, saidplatesbeing provided with bolt holes corresponding toholes in the central part of each blade, and bolts passing through corresponding holes connecting the respective plates with like faces of'the blades.

6. A propeller composed of two or more hollow blades and a central block of wood shaped to fit the hollow central portions of he propeller blades and extending partiallyinto the hollow interiors of said blades.

7. The combination with a propeller flange, of die-formed sections welded or brazed together at the leading and trailing edges, joined together at the center as seetors of the circle constituting the hub of the propeller, two reinforcing steel plates at the center, a block of wood shaped in conformity to the hollow interior of the propeller disposed at the center and bolts traversing the blades, the reinforcing plates, the wood block and propeller flange.

8. A hollow metal propeller comprising shaped surface plates joined to form a unitary propeller structure having a hollow hub, and a reinforcing member within the hub and extending for a considerable distance into the'hollow blade.

9. A hollow metal propeller comprising shaped surface plates joined to form a unitary propeller structure having a hollow hub, and a solid reinforcing block within the hub having projections extending into the hollow blades.

10. A hollow metal propeller comprising shaped surface plates joined to form a unitary propeller structure having a hollow hub and a block of wood within the hollow propeller at the hub.

11. A hollow metal propeller comprisin 5 shaped surface plates joined to form a uni ta propeller structure havin a hollow hub an a block of wood within t e hollow pro- In testimony whereof I have signed this specification.

FREDERICK'H. LUENSE. 

